Disinfecting aqueous foam, process for preparing same and use thereof

ABSTRACT

The present invention relates to a foam consisting of a dispersion of gas bubbles in a foaming solution comprising, per litre of solution, (i) from 0.05 to 1.5% by weight of one or more foaming organic surfactant(s), (ii) from 0.05% to 0.8% by weight of one or more organic gelling or viscosifying agent(s), (iii) from 1% to 14% by volume of one or more disinfecting agent(s) and (iv) water, said foam having an expansion between 12.5 and 50. The present invention also relates to the use of such a foam for biological decontamination.

FIELD OF THE INVENTION

The present invention relates to the biological decontamination andparticularly the treatment of materials and/or facilities contaminatedwith pathogenic agents such as bacteria, viruses, and fungi. Moreparticularly, the present invention is applicable to thedecontamination/disinfection of surfaces contaminated with suchpathogenic agents.

Indeed, the present invention relates to a controlled-moisture, gelledor viscosified, aqueous foam, containing at least one disinfecting agentas well as the use thereof for treating surfaces contaminated withpathogenic agents.

STATE OF THE RELATED ART

The use of biological agents as weapons is not a novel idea. Historyshows that such a use has existed since before the discovery ofmicro-organisms. Whether through the contamination of wells withinfected corpses or the distribution of blankets of smallpox sufferersto spread the infection, history shows that the use of pathogenic agentsas a weapon is an age-old concept. More recently, the anthrax sporebooby-trapped letter attack that occurred in the United Stated in theautumn of 2001 raised awareness among European and American publicopinion on the reality of the bioterrorist threat.

In the hypothetical case of a biological accident or attack, thepriority for the authorities is to limit the effects on the civilianpopulation. This limiting involves the rapid decontamination of exposedinfrastructures in order to prevent agent propagation and restorebuildings to their use without delay without any persisting exposurerisk. Some difficult-to-access contaminated areas, such as, for example,ventilating ducts or wastewater discharge pipes, need to be rapidlydecontaminated to prevent any spread of pathogenic agents. Therefore,there is a need on the market for means for decontaminating these areas.Such decontaminating means should be suitable for use by filling anenclosed or semi-enclosed space or for spraying onto vertical andhorizontal walls. Furthermore, as identification is not always possibleand the response needs to be rapid, the decontamination solution must,for its part, be effective against a wide range of biological agents.

A plurality of biological and/or chemical decontamination foams exist,used in the field of Nuclear, Radiological, Biological, Chemical (NRBC)risks.

A first decontamination form DF-100 was developed by Sandia NationalLaboratories. The formulation of this solution comprises a surfactant, areagent compound, i.e. liquid hydrogen peroxide and water. A secondsolution was developed: DF-200 or EasyDECON® 200 [1]. This solution isan enhanced version of DF-100, as it further contains a bleachingactivator which is glycerol diacetate. The latter compound makes itpossible to increase the reaction rate, enhance the reaction yield anddo away with the need to adjust the pH. This foam is multi-purpose as itis effective for neutralising chemical warfare agents such as sarin,mustard gas, O-ethyl S-[2-(diisopropylamino)ethyl]methylphosphonothioate (or VX) and soman, industrial chemical toxins andbiological agents such as B. anthracis and Y. pestis. It is notcorrosive and the use thereof does not create harmful by-products. Asfurnished in the patent application US 2007/0249509 [2], the completeformulation of DF-200 foam consists, as a percentage by weight withrespect to the total weight of the formulation, of:

-   -   1.8% benzalkonium chloride (cationic surfactant);    -   0.5% ADOGEN 477™ (cationic hydrotrope);    -   1.1% hexylene glycol (solvent);    -   0.4% 1-dodecanol (fatty acid);    -   12% sorbitol (sorbent additive which acts as a drying agent to        produce a granulated form);    -   4.7% of a mixture of potassium carbonate and potassium        bicarbonate, used as a strong base;    -   1.8% glycerol diacetate (water-soluble bleaching activator);    -   4.6% polyethylene glycol (water-soluble polymer particularly        used to increase foam stability);    -   7.8% hydrogen peroxide urea (decontaminating agent) and    -   65.3% water.

The performances of the DF-100 and DF-200 solutions on chemical andbiological agents such as, for example, Bacillus globigii (simulatingAnthrax), Bacillus anthracis and Yersinia pestis are accessible on theInternet [3].

CASCAD™ Surface Decontamination Foam (CASCAD™ SDF), marketed byAllen-Vanguard, has the properties of decontaminating buildingscontaminated with biological and chemical agents, as well as radioactiveparticles, and of confining an explosion. This solution was developed todecontaminate buildings without damaging the various contaminatedmaterials. It is the enhanced version of CASCAD™ (for “Canadian AqueousSystem for Chemical/biological Agent Decontamination”) decontaminationsolution [4]. The latter is a solution developed to decontaminatevessels, aircrafts and vehicles in the event of suspected or provencontamination.

CASCAD™ SDF foam has been optimised for use over a longer period of timeand under more restrictive weather conditions. It is presented in theform of a powder which can be dispensed, after adding water, in liquidform or in foam form according to a wide range of dispersion equipment.After application and a sufficient contact time, the solution may berinsed or displaced using pumps.

CASCAD™ SDF foam is produced by mixing and reacting two liquid solutionstogether. The latter are prepared using three separate reagents whichhave the following chemical compositions:

-   -   GPA-2100 (decontaminant): solid reagent in powder form        consisting of a sodium salt of dichloroisocyanuric acid (70 to        100% by weight);    -   GPA-2100 (buffer): solid reagent in powder form consisting of        sodium tetraborate (10 to 30% by weight), sodium hydroxide (1 to        5% by weight) and sodium carbonate (40 to 65% by weight); and    -   GCE-2000 (surfactant): liquid reagent consisting of myristic        sodium sulphate (10 to 30% by weight), sodium olefin sulphonate        (C14-16) (10 to 30% by weight), denatured ethanol (3 to 9% by        weight), alcohols (C10-16) (5 to 10% by weight), sodium sulphate        (3 to 7% by weight), sodium xylene sulphonate (1 to 5% by        weight) and a mixture of sodium and ammonium salts with water        and a co-solvent (quantity greater than 9% by weight).

A method for preparing CASCAD™ SDF foam is particularly provided inAnnex B of [5]. This report proposes a comparative study of thedecontamination efficacy of a plurality of decontamination solutionsincluding DF-200, CASCAD™ SDF and bleach solution, on various materials.This study relates to six decontamination solutions:

-   -   pH-Amended Bleach used in liquid form and composed of 5% sodium        hypochlorite, water and 5% acetic acid to adjust the pH;    -   CASCAD™ SDF (Allen-Vanguard) used in foam form;    -   Decon Green used in liquid form, the active agent being hydrogen        peroxide;    -   EasyDECON® 200 (DF-200) (EFT Holdings, Inc.) used in liquid        form;    -   Spor-Klenz® RTU (STERIS Corporation) used in liquid form, the        active agents being hydrogen peroxide and peracetic acid;    -   Peridox® RTU (CET, LLC) used in liquid form, the active agents        being hydrogen peroxide and peracetic add.

The results obtained in terms of the decontamination efficacy withrespect to Bacillus anthracis spores and presented in [5] demonstratethat porous materials such as concrete, asphalt and treated wood aremore difficult to decontaminate than non-porous materials such as glass,stainless steel, aluminium, porcelain and granite. The most effectivesolution for decontaminating spores is CASCAD™ SDF foam. It is effectiveboth on porous and non-porous materials. EasyDECON 200 solution and thebleach-based solution are not effective on porous materials such asasphalt and treated wood. For these three solutions, no damage wasobserved on the materials after 60 min of contact time and 7 days afterthe spore count.

In summary, the foams according to the prior art are versatile onchemical and biological agents. They are mostly used by spraying ontothe surfaces to be treated. However, it should be noted that the foamingsolutions from which they are prepared have numerous constituents whichis not only costly but also results in long preparation processes.Finally, the expansion of these foams is not specified and therefore notcontrolled.

The inventors set themselves the aim of developing a foam suitable foruse for treating surfaces contaminated with biological agents, that iseasy to use and, regardless of the surface to be treated, requires nostructure, or costly reagent and generates very little effluent once thetreatment has been carried out.

DESCRIPTION OF THE INVENTION

The aims set and further aims are achieved by the invention whichrelates to a controlled-moisture aqueous foam and method for treatingand disinfecting contaminated surfaces.

The present invention is an aqueous foam with moisture controlled by aspecific generator. These physicochemical properties enable thestability thereof over time in foam form by means of the use in theformulation of a viscosifying agent. The expansion control by thegenerator makes it possible to obtain stable foams that are effectiveagainst pathogenic agents with a moisture percentage between 2% and 8%,and preferentially between 4% and 5%.

The use and retrieval of the foam according to the invention are novel.Indeed, the controlled expansion between 12.5 and 50 and advantageouslybetween 20 and 25 allows use by spraying or spreading in a “layer” (orfloating) of a foam that is stable and adherent to inclined, horizontalor vertical walls, floors and ceilings. The foam according to thepresent invention may also be used for filling enclosed or semi-enclosedenvironments optionally of variable and large volume. This foam may beretrieved by suction or by merely allowing to evaporate, the evaporationleaving non-toxic traces.

Therefore, the present invention relates to a foam suitable forevaporation and suction which represents a completely novel concept withregard to foams according to the prior art. Furthermore, in terms ofliquid effluents, a foam suitable for suction generates very little, anda form suitable for evaporation generates none.

More particularly, the present invention relates to a foam consisting ofa dispersion of gas bubbles in a foaming solution comprising, per litreof solution:

-   -   from 0.05% to 1.5% by weight of a foaming organic surfactant or        of a mixture of foaming organic surfactants,    -   from 0.05% to 0.8% by weight of an organic gelling or        viscosifying agent or of a mixture of organic gelling or        viscosifying agents,    -   from 1% to 14% by volume of a disinfecting agent or of a mixture        of disinfecting agents and    -   water,    -   said foam having an expansion between 12.5 and 50.

Due to the composition thereof, the disinfecting aqueous foam accordingto the present invention has the advantages of controlled-lifetime foamsconventionally used in radioactive decontamination treatment (see, inthis respect, the international application WO 2004/008463 [6]).However, the disinfecting aqueous foam according to the presentinvention differs from the foams described in the internationalapplication WO 2004/008463 by the absence of radiologicaldecontamination agent and by the expansion thereof.

Note that, in one particular embodiment of the invention, the foamingaqueous solution used for preparing the disinfecting aqueous foamaccording to the present invention only contains, in addition to water,three types of compounds which corresponds to a simplified formulationwith respect to the formulations of the foams according to the priorart. Such a foaming aqueous solution therefore consists of

-   -   from 0.05% to 1.5% by weight of a foaming organic surfactant or        of a mixture of foaming organic surfactants,    -   from 0.05% to 0.8% by weight of an organic gelling or        viscosifying agent or of a mixture of organic gelling or        viscosifying agents,    -   from 1% to 14% by volume of a disinfecting agent or of a mixture        of disinfecting agents and    -   water,

The foaming solution used for preparing the disinfecting aqueous foamcomprises, as a solvent, water, thus justifying the description foamingaqueous solution. The term “water” denotes tap water, deionised water ordistilled water. Advantageously, the disinfecting aqueous foam accordingto the invention may be a neutral, acidic or basic foam, according tothe disinfecting agent(s) contained therein and the pH conditionsrequired for satisfactory disinfecting efficacy thereof. Those skilledin the art will be able to determine the most suitable pH and modify thepH of the foaming aqueous solution accordingly.

The disinfecting aqueous foam according to the invention is acontrolled-expansion and therefore a controlled-moisture foam. By way ofreminder, a foam is frequently characterised by the expansion thereofdefined, under normal temperature and pressure conditions, by thefollowing relation (I):

F=(Vol_(gas)+Vol_(liquid))/Vol_(liquid)=Vol_(foam)/Vol_(liquid)  (I)

Consequently, the moisture of a foam corresponds to the reciprocal ofthe expansion thereof and therefore is defined by the ratioVol_(liquid)/Vol_(foam).

The disinfecting aqueous foams according to the present invention havean expansion between 12.5 and 50, particularly between 15 and 30 and, inparticular, between 20 and 25, which corresponds to a liquid fraction ormoisture of the foam between 2 and 8%, particularly between 3.33 and6.67% and, in particular, between 4 and 5%. Note that the liquid volume(Vol_(liquid)) in the above ratios corresponds to the volumes of thevarious compounds initially mixed to prepare the foaming aqueoussolution and, in particular to the sum of the volume of the foamingorganic surfactant(s), the volume of the organic gelling or viscosifyingagent(s), of the disinfecting agent(s) and the volume of water.

The foaming aqueous solution generating the disinfecting aqueous foamaccording to the invention comprises at least one foaming organicsurfactant. The term “organic surfactant” denotes an organic moleculeincluding a lipophilic (apolar) part and a hydrophilic (polar) part. Theterm “foaming organic surfactant” denotes an organic surfactant asdefined above further having a hydrophilic-lipophilic balance (HLB)between 3 and 8. By way of reminder, the HLB value of a surfactant maybe readily obtained by means of the Davies formula [7] and the HLBcharts for different chemical groups, available for those skilled in theart.

More particularly, the foaming aqueous solution forming the disinfectingaqueous foam according to the invention may comprise a single foamingorganic surfactant or a mixture of at least two foaming organicsurfactants chosen from non-ionic foaming surfactants, anionic foamingsurfactants, cationic foaming surfactants, amphoteric surfactants,Bolaform type structural surfactants, Gemini type structural surfactantsand polymeric surfactants.

Advantageously, the foaming aqueous solution used within the scope ofthe present invention comprises a single foaming organic surfactant or amixture of at least two foaming organic surfactants chosen fromnon-ionic foaming surfactants, anionic foaming surfactants and cationicfoaming surfactants. In the mixtures of foaming organic surfactants, atleast two surfactants are chosen in the same family or in two differentfamilies chosen from among non-ionic foaming surfactants, anionicfoaming surfactants and cationic foaming surfactants.

By way of reminder, non-ionic (or neutral) surfactants are compoundswherein the surfactant properties, particularly the hydrophily, areprovided by non-charged functional groups such as an alcohol, an ether,an ester or an amide, and may contain heteroatoms such as nitrogen oroxygen. Due to the low hydrophilic contribution of these functions, thefoaming non-ionic surfactant compounds are generally polyfunctional.Within the scope of the present invention, the foaming non-ionicsurfactants are particularly chosen from alkyl alkoxylates; fattyalcohol alkoxylates; fatty amine alkoxylates; fatty acid alkoxylates;oxo alcohol alkoxylates; alkylphenol alkoxylates; alkyl ethoxylates;fatty acid ethoxylates; fatty amine ethoxylates; fatty acid ethoxylates;oxo alcohol ethoxylates; alkylphenol ethoxylates such as, for example,octylphenol and nonylphenol ethoxylates; alcohols, α-diols,polyethoxylated and poly-propoxylated alkylphenols having a fatty chainincluding, for example, 8 to 18 carbon atoms, the number of ethyleneoxide or propylene oxide groups optionally being particularly from 2 to50; polyethylene and polypropylene oxide complex polymers; ethylene andpropylene oxide copolymers; polyethylene and polypropylene oxide blockcopolymers such as, for example, POE-POP-POE triblock copolymers;ethylene and propylene oxide condensates on fatty alcohols;polyethoxylated fatty amides having, preferably, 2 to 30 moles ofethylene oxide; polyethoxylated ethers having, preferably, 2 to 30 molesof ethylene oxide; monoesters (monolaurate, monomyristate, monostearate,monopalmitate, monooleate, etc.) and polyesters of fatty acids andglycerol; polyglycerolated fatty amides comprising on average from 1 toS and, more especially, from 1.5 to 4 glycerol groups; oxyethylenatedsorbitan fatty acid esters including 2 to 30 moles of ethylene oxide;monoesters (monolaurate, monomyristate, monostearate, monopalmitate,monooleate, etc.) and polyesters of fatty acids and sorbitan, monoestersof sorbitan polyoxyethylene; sucrose esters of fatty acids;polyethyleneglycol esters of fatty acids; alkyl polyglucosides; N-alkylglucamine derivatives and amine oxides such as alkyl(C₁₀-C₁₄) amineoxides or N-acylaminopropylmorpholine oxides; polyols (surfactantsderived from sugars) in particular glucose alkylates such as for exampleglucose hexanate; surfactants derived from glucoside (sorbitol laurate)or polyols such as glycerolated alcohol ethers; alkanolamides andmixtures thereof. More particularly, by way of foaming non-ionicsurfactants, it is possible to use the foaming non-ionic surfactantsdescribed in the international application WO 2004/008463 [6]. Such asurfactant is, for example, chosen in the family of alkylpolyglucosidesor alkylpolyetherglucosides, biodegradable natural derivatives ofglucose. These are for example “ORAMIX CG-110” from SEPPIC, or “Glucopon215 CS” from COGNIS.

Anionic surfactants are surfactants wherein the hydrophilic part isnegatively charged. A foaming anionic surfactant suitable for use withinthe scope of the present invention is typically chosen in the groupconsisting of sulphuric acid esters, phosphoric acid esters, alkyl oraryl sulphonates, alkyl or aryl sulphates, alkyl or aryl phosphates,alkyl or aryl sulphosuccinates or alkyl or aryl sarcosinates associatedwith a counterion such as an ammonium ion (NH4⁺), a quaternary ammoniumsuch as tetrabutylammonium, and cations and particularly alkalinecations, said cations being such as Na⁺, Li⁺, Ca⁺, Mg²⁺, Zn²⁺ and K⁺. Byway of foaming anionic surfactants, it is, for example, possible to usetetraethylammonium paratoluenesulphonate, sodium dodecylsulphate (orSDS), sodium laurylsarcosinate (or sarcosyl), sodium palmitate, sodiumstearate, sodium myristate, sodium di(2-ethylhexyl) sulphosuccinate,methylbenzene sulphonate and ethylbenzene sulphonate.

Cationic surfactants have at least one hydrocarbon chain and a polarhead, the hydrophilic part of said agent being positively charged. Afoaming cationic surfactant suitable for use within the scope of thepresent invention is advantageously chosen from quaternary ammoniumscomprising at least one C₄-C₂₂ aliphatic chain associated with ananionic counterion chosen particularly from boron derivative such astetrafluoroborate or halide ions such as F⁻, Br⁻, I⁻ or Cl⁻. By way offoaming cationic surfactants suitable for use, mention may be made oftetrabutylammonium chloride, tetradecylammonium bromide,tetradecyltrimethyl ammonium bromide (TTAB), alkylpyridinium halidescarrying an aliphatic chain and alkylammonium halides.

In one particular embodiment, the foaming organic surfactant(s) is/arechosen in the group consisting of carboxylic acid salts, sulphonic acidsalts, sulphate salts, sulphuric acid ester salts, phosphoric acid estersalts, alkylpolyglucosides and amine oxides.

In the foaming aqueous solution forming the disinfecting aqueous foamaccording to the present invention, the surfactant or the mixture of atleast two surfactants is present at a rate of 0.05 to 1.5% by weight,particularly from 0.08 to 1.3% by weight and, in particular, from 0.1 to1.1% by weight per litre of solution.

Furthermore, the foaming aqueous solution forming the disinfectingaqueous foam according to the present invention comprises, in additionto the surfactant(s) cited above, an organic gelling or viscosifyingagent or a mixture of at least two organic gelling or viscosifyingagents in a content between 0.05% and 0.8% by weight, particularly from0.1 to 0.5% by weight and, in particular, from 0.15 to 0.3% by weightper litre of solution.

Advantageously, such an organic gelling agent is a biodegradable,pseudoplastic agent enabling the foam to be readily sprayable and have alifetime between 30 min and 6 hours and therefore suitable for theperiod of biological decontamination and use.

This or these gelling and/or viscosifying agent(s) is/are, moreparticularly, chosen from water-soluble polymers, hydrocolloids,heteropolysaccharides such as, for example, trisaccharide branched-chainpolyglucoside polymers, cellulose derivatives and polysaccharides suchas polysaccharides containing glucose as a single monomer. By way ofparticular examples, the gelling or viscosifying agent(s) suitable foruse within the scope of the present invention is/are chosen in the groupconsisting of xanthan gum, guar gum, agar-agar, carrageenan, sodiumalginate, caseinate, gelatin, pectin, starch, cellulose,2-hydroxyethylcellulose (HEC) and chitosan.

Finally, the foaming aqueous solution forming the disinfecting aqueousfoam according to the present invention comprises, in addition to thefoaming organic surfactant(s) and the gelling or viscosifying agent(s)cited above, a disinfecting agent or a mixture of at least twodisinfecting agents at a content between 1% and 14% by volume.

The disinfecting agent or the mixture of disinfecting agents may bepresent in the foaming aqueous solution at a quantity between 1 and 10%by volume, particularly between 2 and 7.5% by volume and, in particular,of the order of 5% (i.e. 5%±1%) by volume per litre of solution. Thesespecific ranges are particularly used for surfaces which are neithermade of metal, or steel and for which no reaction with the disinfectingagent(s) has been demonstrated.

Alternatively and particularly for metal or steel surfaces, the contentof disinfecting agent or mixture of at least two disinfecting agents istypically between 5% and 14% by volume and, in particular, of the orderof 12% (i.e. 12%±1%) by volume per litre of solution. In this scenario,the disinfecting agent(s) may react with such surfaces such as aluminiumsurfaces.

The disinfecting agent(s) suitable for use within the scope of thepresent invention belong(s) to the biocidal products as defined by theregulations concerning the marketing and use of biocidal products (EURegulation No. 528/2012 of 22 May 2012 [8]). These biocidal productsrepresent all of the substances and mixtures, consisting of one or aplurality of active molecule(s), with the intention of destroying,deterring, rendering harmless, preventing the action of, or otherwiseexerting a controlling effect on, any harmful living organisms bychemical or biological action. These products are divided, according tothe applications thereof, into four groups which are (i) disinfectingagents, (ii) protective products aimed at preventing microbial and algaldevelopment, (iii) pest control products and (iv) other biocidalproducts such as antifouling products or embalming and taxidermistproducts.

Disinfecting agents are products or processes used for disinfecting ordecontaminating contaminated materials and can be applied to inertsurfaces, living tissue or foodstuffs. As such, disinfecting agents areused for treating in particular medical devices, floors and surfacessuch as metal, concrete, brick, ceramic, wood and plastic which arematerials used in critical infrastructures as well as sensitiveequipment.

The efficacy of disinfecting agents is dependent on the spectrum ofaction on the different types of biological agents. As such,bactericidal agents (action on bacteria), fungicidal agents (action onfungi), virucidal agents (action on viruses) and sporicidal agents(action on spores) are defined. Furthermore, each disinfecting agent hasa number of performance criteria, such as (i′) the rate of efficacythereof, (ii′) the decontamination efficacy thereof which is measured bya reduction factor of an initial contaminant population under the effectof the disinfectant (initial population/final population aftertreatment) or by the reduction in log₁₀ of this factor and (iii′) thecompatibility thereof with construction materials. Disinfecting agentsare therefore classified according to the disinfection efficacy thereofand the terms high-, intermediate- and low-level disinfectiondisinfecting agents are used.

Within the scope of the present invention, the disinfecting agent(s)used is/are chosen from high-level disinfection disinfecting agents i.e.disinfecting agents having a factor (initial contaminantpopulation/final population after treatment) greater than 10⁶.Advantageously, these factors are chosen from chlorinated products,aldehydes and oxidants.

Chlorinated products are disinfecting agents with a broad spectrum ofactivity since they are bactericidal, virucidal, fungicidal andsporicidal. The action time thereof is rapid and equal to the dryingtime thereof. However, they are subject to factors influencing theactivity thereof such as the pH and temperature. Furthermore, theactivity thereof is inhibited in the presence of heavy metal ions, abiofilm, dissolved organic matter, at low temperature, at low pH, or inthe presence of UV radiation. They are used as surface, liquid effluentand equipment disinfectants.

By way of examples of chlorinated products suitable for use asdisinfecting agents within the scope of the present invention, mentionmay be made of chlorine, sodium hypochlorite (bleach solution) andchlorine dioxide. Note that the pH of sodium hypochlorite which is 11 onaverage may be adjusted so that it is between 5 and 8. Indeed, at thispH, sodium hypochlorite is more effective as a disinfectant and probablybecomes less corrosive for materials.

Aldehydes have a broad spectrum of activity as they are bactericidal,fungicidal, virucidal and sporicidal. They are used in liquid or gasform for disinfecting surfaces, equipment, premises and medical devices.They have the action of inducing micro-organism nucleic acid and proteindenaturation.

By way of examples of aldehydes suitable for use as a disinfecting agentwithin the scope of the present invention, mention may be made ofglutaraldehyde and succinic aldehyde.

Oxidants have a broad spectrum of activity as they are bactericidal,fungicidal, virucidal and sporicidal. The efficacy thereof is superiorat an acidic pH and they are inhibited by the presence of organicmatter. They have the action of destroying organic membranes. They aremainly used in vapour form for disinfecting surfaces and equipment.

By way of examples of oxidants suitable for use as a disinfecting agentwithin the scope of the present invention, mention may be made ofperoxides such as hydrogen peroxide; activated peroxides such ashydrogen peroxide+bicarbonate, hydrogen peroxide+urea, hydrogenperoxide+peracetic acid and hydrogen peroxide+iron (Fenton's reagent);hydroperoxycarbonates; peracetic acid; sodium perborate; sodiumpercarbonate optionally perhydrated; sodium peroxysilicate; sodiumperoxypyrophosphate; sodium peroxysilicate and aryloxides such asarylbenzenesulphonates.

In one particular embodiment of the invention, the foaming disinfectingagent(s) is/are chosen in the group consisting of chlorinated productsand oxidants. More particularly, the foaming disinfecting agent(s) issodium hypochlorite and hydrogen peroxide.

The gas used for generating the disinfecting aqueous foam according tothe invention may be any gas. It may particularly be chosen in the groupconsisting of air, oxygen, carbon dioxide, helium, argon and nitrogen.Advantageously, the gas used within the scope of the present inventionis air. As such, the disinfecting aqueous foam according to theinvention consists of a dispersion of air bubbles in a foaming solutionas defined above.

By way of particular examples of disinfecting aqueous foam according tothe invention, mention may be made of:

(1) a dispersion of bubbles of gas and particularly of air in a foamingsolution comprising (or consisting of) per litre of solution:

-   -   from 0.1 to 1.1% by weight of a foaming organic surfactant or of        a mixture of foaming organic surfactants,    -   from 0.15% to 0.3% by weight of an organic gelling or        viscosifying agent or of a mixture of organic gelling or        viscosifying agents,    -   from 2% to 7.5% by volume and particularly of the order of 5% by        volume of a disinfecting agent or of a mixture of disinfecting        agents and    -   water;

(2) a dispersion of bubbles of gas and particularly of air in a foamingsolution comprising (or consisting of) per litre of solution:

-   -   from 0.1 to 1.1% by weight of a foaming organic surfactant or a        mixture of foaming organic surfactants,    -   from 0.15% to 0.3% by weight of an organic gelling or        viscosifying agent or of a mixture of organic gelling or        viscosifying agents,    -   from 5% to 14% by volume and particularly of the order of 12% by        volume of a disinfecting agent or of a mixture of disinfecting        agents and    -   water;

(3) a dispersion of bubbles of gas and particularly of air in a foamingsolution comprising (or consisting of) per litre of solution:

-   -   from 0.1 to 1.1% by weight of an alkylpolyglucoside,    -   from 0.15% to 0.3% by weight of xanthan gum,    -   from 2% to 7.5% by volume and particularly of the order of 5% by        volume of sodium hypochlorite or hydrogen peroxide and    -   water;

(4) a dispersion of bubbles of gas and particularly of air in a foamingsolution comprising (or consisting of) per litre of solution:

-   -   from 0.1 to 1.1% by weight of an alkylpolyglucoside,    -   from 0.15% to 0.3% by weight of xanthan gum,    -   from 5% to 14% by volume and particularly of the order of 12% by        volume of sodium hypochlorite or hydrogen peroxide and    -   water;    -   the expansion of these foams being as defined above.

The present invention relates to a method for preparing the disinfectingaqueous foam as defined above. The latter may be readily prepared, atambient temperature (i.e. at a temperature of the order of 23′C±5′C),using techniques known to those skilled in the art.

The first step of this preparation method consists of mixing togetherwater, the foaming organic surfactant(s), the organic gelling orviscosifying agent(s) or the disinfecting agent(s), prior to foamgeneration. This mixing may be performed by adding the components in onego, by group or in succession. In one particular embodiment, it may beenvisaged to prepare a first solution by mixing together water, thefoaming organic surfactant(s) or the organic gelling or viscosifyingagent(s) and only adding the disinfecting agent(s) to this solutionimmediately prior to generating the foam.

The second step of this preparation method consists of generating thefoam. This step may be performed by means of any system for generatingfoam according to the prior art and known to those skilled in the art.It consists of any device for gas-liquid mixing, particularly bymechanical stirring, by bubbling, by static mixer optionally containingbeads, by microbead tube foam generator or devices described in theinternational application WO 02/043847 [9], or any other deviceparticularly nozzle or venturi systems enabling high flow rates between1 and 1000 m³/hr. More particularly, the invention advantageously uses afoam generator suitable for controlling the moisture of the foamgenerated. This moisture control is performed by measuring the mixedsolution and air flow rate. The formulations according to the inventionmake it possible to readily obtain a foam with the latter type ofgenerator wherein the moisture is between 2 and 8%, particularly between3.33 and 6.67% and, in particular, between 4 and 5%.

The present invention relates to the use of a disinfecting aqueous foamas defined above for treating a surface likely to be contaminated withat least one biological agent. More particularly, the present inventionrelates to a method for treating a surface likely to be contaminatedwith at least one biological agent consisting of contacting said surfacewith a disinfecting aqueous foam.

The term “treating a surface likely to be contaminated with at least onebiological agent” denotes within the scope of the present inventionreducing the quantity of biological agents present on the surface priorto the treatment according to the invention. This reduction may involveeliminating or destroying these agents and/or the conversion thereofinto less harmful elements. As such, the expression “treatment of asurface” is equivalent and interchangeable with the expressions“disinfection of a surface” and “biological decontamination of asurface”.

Any surface likely to be contaminated by one or a plurality ofbiological agent(s) may undergo a treatment method according to thepresent invention. The term “surface” denotes the external part of anobject or solid body, limiting same in all directions. It is possible,for the same object (or same solid body), to conceptually definedifferent surfaces. The invention is applicable to any type of surfaceregardless of the geometry thereof. The latter may be simple, such as aperfectly planar surface, or complex, such as rough surface, or haveunobstructed cavities, regardless of the material forming the surfaceand the rest of the object on which it depends.

Advantageously, within the scope of the present invention, the surfaceof the object to be treated may be an inorganic or organic surface andparticularly a surface made of metal such as aluminium, metal alloy,steel and particularly stainless steel, tinplate, silicon, glassgenerally containing silicates, silica glass, ceramic, brick, porcelain,cement, concrete, asphalt, stone, granite, wood, clay, plastic or anyone of the combinations thereof.

The surface to be treated or the object for which the surface is to betreated according to the method according to the present invention mayhave any size, shape and orientation. It may consist of large surfacessuch as a road or the wall, ceiling and/or floor of a largeinfrastructure such as building, airport, underground railway or hotel,intermediate-sized installations such as an industrial object like amachine implemented in the agri-food industry, vehicle, framework,aircraft, tank, restaurant kitchen, cold store, sanitary block orcontainer, and small-sized installations such as medical devices, pipes,or a weapon.

The term “biological agent” denotes natural micro-organisms such asbacteria, archaea, parasites, protozoa, fungi, yeasts or viruses, thetoxins produced or not by such micro-organisms, protein type pathogenicagents such as prions and genetically modified micro-organisms.

By way of particular and non-exhaustive examples of biological specieslikely to be eliminated by the method according to the invention,mention may be made of any type of micro-organisms such as bacteria,spores particularly Bacillus anthracis spores, viruses, fungi, yeastsand toxins. The species or biological species which are eliminated,destroyed, inactivated, by the foam according to the invention areessentially species or bio-toxic elements like pathogenic spores suchas, for example, Bacillus anthracis spores, Gram − bacteria (such as forexample Yersinia pestis, Francisella tularensis, Pseudomonas aeruginosa,Salmonella thyphimurium and Legionella sp) and Gram+bacteria(Staphylococcus aureus, Clostridium sp and Streptococcus sp), toxinssuch as, for example botulinum toxin, ricin or curcin, and viruses suchas, for example, haemorrhagic fever viruses (such as Ebola for example)or coronaviruses (such as SARS for example).

In the method according to the invention, the contacting between thesurface to be treated and the disinfecting aqueous foam is direct andmay be carried out in various ways in “static” mode.

In a first embodiment, the contacting consists of applying, on thesurface to be treated as defined above, the disinfecting aqueous foam asdefined above. This first embodiment may involve application by sprayingor by floating i.e. spreading in layers. In this first embodiment, thefoam may be generated at the time of contacting (spraying) or, on theother hand, prior to this contacting (floating), in open or closedspaces. The layer of disinfecting aqueous foam sprayed or spread may befrom 0.5 cm to 5 cm and advantageously from 1 to 2 cm.

In a second embodiment, the contacting consists of filling thestructures having a surface to be treated as defined above with thedisinfecting aqueous foam as defined above. These structures areparticularly enclosed or semi-enclosed environments which can be ofvariable and large volume. This second embodiment is particularlysuitable for treating sites and infrastructures that are accessible orinaccessible for humans such as ventilation pipes or items containing aplurality of non-movable components such as aircraft sanitaryinstallations. Indeed, the foam limits liquid dead volumes, occupyingthe entire space and wetting all of the surfaces such as pipes, gratingsor the gap between non-removable objects.

The contacting time ranges from a few minutes to the complete drying ofthe disinfecting aqueous foam. Advantageously, the contacting time isgreater than 10 min, particularly greater than 20 min, and moreparticularly greater than 30 min, which is the time suitable forbiological decontamination and use.

In the method according to the present invention, following thecontacting step, said sprayed or floated foam is allowed to dry byevaporation or said foam used in filling mode is allowed to drain.

Furthermore, the method according to the present invention may have,following the contacting step, a step aimed at retrieving the foam orthe residue of this foam. Advantageously, this retrieval may beperformed using suction. In the event of foam remaining i.e. beforecomplete drying, the latter is suctioned. On the other hand, if theliquid fraction of the foam is allowed to evaporate and therefore, ifthe foam has been allowed to dry, only non-toxic dried residue ispresent on the treated surface, and the latter is retrieved by suctionor by wiping particularly using a wipe or a sponge. As this driedresidue is non-toxic, it can also be left on the treated surface withoutretrieval thereof.

Further features and advantages of the present invention will emerge onreading the examples hereinafter given by way of illustration and notrestriction and with reference to the appended figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the mean evaluation of the decontamination efficacy of afoam according to the invention containing different concentrations ofsodium hypochlorite (FIG. 1A) or different concentrations of hydrogenperoxide (FIG. 1B).

FIG. 2 shows the mean rate of decontamination of a foam according to theinvention containing sodium hypochlorite (FIG. 2A) or hydrogen peroxide(FIG. 2B).

FIG. 3 is a schematic representation of the experimental protocol usedfor evaluating the efficacy of a foam according to the invention onearthenware tiles.

FIG. 4 shows the evaluation of the decontamination efficacy of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide on earthenware tiles (FIG. 4A) or on aluminium plate (FIG. 4B).

FIG. 5 shows the evaluation of the decontamination efficacy of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide on vertical walls.

FIG. 6 shows the evaluation of the decontamination efficacy of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide in filling mode.

FIG. 7 shows the evaluation of the decontamination efficacy of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide and having different moisture percentages.

FIG. 8 shows the evaluation of the decontamination efficacy of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide after ageing of the initial foaming solutions.

FIG. 9 shows a comparison of the foamability and drainage at t=0, t=1 wkand t=5 wks of storage, of a foam according to the invention containingsodium hypochlorite (FIG. 9A) or hydrogen peroxide (FIG. 98).

FIG. 10 shows the slippage kinetics of an application of a foamaccording to the invention containing sodium hypochlorite or hydrogenperoxide on a wipe-off marker whiteboard.

FIG. 11 shows the evaporation kinetics of a neutral foam (FIG. 11A) orof a foam according to the invention containing sodium hypochlorite(FIG. 11B) or hydrogen peroxide (FIG. 11C), all of these foamsoptionally containing 1.5 g/l or 3 g/l of xanthan, as viscosifyingagent.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS I. Formulations Used forFoam.

The various formulations of the following solutions used during thetests presented hereinafter are contained in Table 1 hereinafter:

TABLE 1 Concentration per Litre of Name of formulation Compositionfoaming solution Neutral, 1.5 g/l of Xanthan H₂O 839 ml/L Glucopon 11g/L 10 g/l Xanthan 150 ml/L Neutral, 2 g/l of Xanthan H₂O 789 ml/LGlucopon 11 g/L 10 g/l Xanthan 200 ml/L Neutral, 2.5 g/l of Xanthan H₂O739 ml/L Glucopon 11 g/L 10 g/l Xanthan 250 ml/L Neutral, 3 g/l ofXanthan H₂O 689 ml/L Glucopon 11 g/L 10 g/l Xanthan 300 ml/L 1% NaOClH₂O 768 ml/L Glucopon 11 g/L 10 g/l Xanthan 150 ml/L 14% NaOCl  71 ml/L2% NaOCl H₂O 696 ml/L Glucopon 11 g/L 10 g/l Xanthan 150 ml/L 14% NaOCl143 ml/L 3% NaOCl H₂O 625 ml/L Glucopon 11 g/L 10 g/l Xanthan 150 ml/L14% NaOCl 214 ml/L 4% NaOCl H₂O 553 ml/L Glucopon 11 g/L 10 g/l Xanthan150 ml/L 14% NaOCl 286 ml/L 5% NaOCl and 1.5 g/l H₂O 482 ml/L XanthanGlucopon  11 ml/L 10 g/l Xanthan 150 ml/L 14% NaOCl 357 ml/L 5% NaOCland 2 g/l Xanthan H₂O 431 ml/L Glucopon 11 g/L 10 g/l Xanthan 200 ml/L14% NaOCl 358 ml/L 5% NaOCl and 2.5 g/l H₂O 381 ml/L Xanthan Glucopon 11g/L 10 g/l Xanthan 250 ml/L 14% NaOCl 358 ml/L 5% NaOCl and 3 g/lXanthan H₂O 331 ml/L Glucopon 11 g/L 10 g/l Xanthan 300 ml/L 14% NaOCl358 ml/L 7.5% NaOCl H₂O 303 ml/L Glucopon 11 g/L 10 g/l Xanthan 150 ml/L14% NaOCl 536 ml/L 1% H2O2 H₂O 806 ml/L Glucopon 11 g/L 10 g/l Xanthan150 ml/L 30% H2O2  33 ml/L 2% H2O2 H₂O 772 ml/L Glucopon 11 g/L 10 g/lXanthan 150 ml/L 30% H2O2  67 ml/L 5% H2O2 and 1.5 g/l H₂O 672 ml/LXanthan Glucopon 11 g/L 10 g/l Xanthan 150 ml/L 30% H2O2 167 ml/L H2O25% and 2 g/l Xanthan H₂O 622 ml/L Glucopon 11 g/L 10 g/l Xanthan 200ml/L 30% H2O2 167 ml/L H2O2 5% and 2.5 g/l H₂O 572 ml/L Xanthan Glucopon11 g/L 10 g/l Xanthan 250 ml/L 30% H2O2 167 ml/L 5% H2O2 and 3 g/lXanthan H₂O 523 ml/L Glucopon 11 g/L 10 g/l Xanthan 300 ml/L 30% H2O2167 ml/L 8% H2O2 H₂O 574 ml/L Glucopon 11 g/L 10 g/l Xanthan 150 ml/L30% H2O2 265 ml/L

II. Biological Test Operating Protocol.

The tests are conducted with spores of Bacillus thuringiensis (Bt) whichis a simili of Bacillus anthracis, in a biosafety cabinet (BSC)allocated to spores in an L2 microbiology laboratory. Petri dishes arecontaminated with 100 μl of a solution containing 10⁸ spores of Bt/ml,i.e. a deposit of 10⁷ spores of Bt, which is allowed to dry completelyunder the hood (approximately 1 hr30).

The foaming solutions are prepared in the laboratory with a staticgenerator with beads. The foams are generated in a 2-litre beaker andthen weighed to determine the moisture of the foam. The foams are thendeposited onto the spores using a spatula.

The foams remain in contact with the spores with the dishes closed, for1 hr to 1 hr30 approximately or according to the test protocol (examplefor the biocidal action rate).

For each dish, the spores are taken up by depositing sterile water onseveral occasions and placed in one or a plurality of Falcon tubes madeup to 45 ml. The Falcon tubes are centrifuged for 15 min at 4000 rpm.

The supernatant is removed and the pellet is re-suspended in 10 ml ofliquid Luria-Broth (LB) nutrient broth, and then vortexed. If the samedish has required the use of a plurality of Falcon tubes, the tubes arecombined into one. The Falcon tubes are placed in an incubator at 30′Cfor 1 hr.

This incubation in LB medium enables the initiation of the desporulationof Bacillus thuringiensis spores which are converted into vegetativeform at the correct temperature, and prolonged contacting of thesubstrate with the medium in order to retrieve a maximum number ofspores present on the substrate. These vegetative forms may grow in theform of colonies on a solid nutrient medium (agar) in Petri dishes andthus be counted visually. This enables an estimation of the number ofinitial spores inactivated.

For each of the tubes incubated at 30′C, a series of ten-fold (factorsof 10) successive dilutions by volume is produced with liquid LB(dilution to 10⁸ or to one hundred millionth). Finally, 1 ml is taken upinto each of the tubes of each series of dilutions, and is thendeposited onto the bottom of a sterile empty Petri dish.

LB agar medium is then poured into the dish (inoculation throughout).The dishes are then placed in an incubator at 30′C for approximately 20hrs. The colonies are counted one by one and a mean live spore count iscalculated. A test containing no disinfectant, referred to as Neutral,is conducted at least once for each test, so as to check that theoperating protocol has been applied correctly.

III. Evaluation of the Biocidal Efficacy of the Formulation.

III.1. Foams with Different Sodium Hypochlorite and Hydrogen PeroxideConcentrations.

Tests are conducted in order to determine the biocidal efficacy atdifferent NaOCl and H₂O₂ concentrations. These tests are conductedaccording to the operating protocol described above and according to theformulations detailed above.

As such, three tests were conducted for 5% NaOCl, two tests for 5% H₂O₂and one test for 1%, 2%, 3%, 4% and 7.5% NaOCl, as well as for 1% and 2%H₂O₂.

The results of these tests are shown in FIGS. 1A and 1B. It emerges thatthe foam according to the present invention with sodium hypochlorite iseffective from a concentration of 1% sodium hypochlorite and that withhydrogen peroxide is effective from a concentration of 2% hydrogenperoxide.

III.2. Evaluation of Foam Decontamination Rates.

Tests are conducted in order to determine the biocidal efficacy rate ofthe NaOCl and H₂O₂ foams. These tests are conducted according to theoperating protocol described above.

The contact time between the foam and the spores is measured with atimer.

Foam/contamination contact times of 30 s, 5 min, 7 min, 10 min, 15 min,30 min, 45 min and 1 hr were tested. However, it is necessary to takeinto account the irreducible treatment time due to the experimentalprotocol (foam retrieval and centrifugation) of approximately 20 min.The foam retrieved is diluted with sterilised water; therefore thedisinfectant is at a lower concentration and the foam is broken down.

The number of reproductions of these tests is shown in Table 2hereinafter:

TABLE 2 Contact time Number of 5% NaOCl tests Number of 5% H₂O₂ tests 30seconds 2 2  5 minutes 1 —  7 minutes 2 2 10 minutes 1 — 13 minutes 2 115 minutes 2 3 30 minutes 2 2 45 minutes 2 2 60 minutes 4 4

The results of these tests are shown in FIGS. 2A and 2B. As such, thefoam containing 5% sodium hypochlorite and that containing 5% hydrogenperoxide neutralise all of the spores (approximately 10⁷ spores) from 5min and 13 min of contact, respectively. It is necessary to add, tothese contact times, the treatment time due to the experimentalprotocol, making it possible to state that the solutions are effectivein 30 min; therefore, both disinfectants are effective in less than onehour.

III.3. Valuation of Decontamination Efficacy of Foams on VariousSubstrates.

Tests are conducted in order to determine the biocidal efficacy of NaOCland H₂O₂ foams on various materials. The tests follow the operatingprotocol described above apart from the depositions which are carriedout on an earthenware tile or on an aluminium plate placed in a Petridish with a contact time between the foam and the contaminated materialof 30 min (FIG. 3).

The contaminated material is placed in a tube with 30 ml of liquidLuria-Broth (LB) nutrient medium and incubated for 1 hr at 30′C. Thisincubation makes it possible to initiate the desporulation of Bacillusthuringiensis spores which are converted into vegetative form andprolong the contact time with the substrate in order to check that nospores remain on the earthenware tile or aluminium plate.

For each of the tubes incubated at 30′C, a series of ten-fold (factorsof 10) successive dilutions by volume is produced with liquid LB(dilution to 101 or to one hundred millionth). Finally, 1 ml is taken upinto each of the tubes of each series of dilutions, and is thendeposited onto the bottom of a sterile empty Petri dish. LB agar mediumis then poured into the dish (inoculation throughout). The dishes arethen placed in an incubator at 30′C for approximately 20 hrs. Thecolonies are counted one by one and a mean live spore count iscalculated. The decontamination factor may be calculated by determiningthe reduction in thousands of spores killed (log₁₀).

The results of these tests conducted on earthenware tile or aluminiumplate are shown in FIGS. 4A and 4B. The foams according to the inventionwith 5% sodium hypochlorite and with 5% hydrogen peroxide are effectiveon earthenware tiles in 30 min. On aluminium plates, only bleach by wayof disinfecting agent was tested and a foam according to the inventioncontaining 5% sodium hypochlorite is also effective in 30 min on such asubstrate.

III.4. Evaluation of Decontamination Efficacy of Foams on Vertical Wall.

Tests are conducted in order to determine the biocidal efficacy of NaOCland H₂O₂ foams on a vertical wall. These tests are conducted accordingto the operating protocol described above with rectangular dishes andaccording to the formulations detailed above.

For these tests on a vertical wall, the foam applied forms a cone, thebase whereof rests on the bottom of the dish and rises up the verticalwall. The contamination zone remains covered by the foam.

For the tests on a vertical wall, one test with the 5% NaOCl foam andtwo tests with a 5% H₂O₂ foam were conducted. The results of these testsare shown in FIG. 5. The 5% NaOCl and 5% H₂O₂ have physicochemicalproperties and a rate of action enabling them to have a sufficientcontact time with the vertical wall to decontaminate the latter.

III.5. Evaluation of Decontamination Efficacy of Foams in Filling Mode.

Tests are conducted in order to determine the biocidal efficacy of NaOCland H₂O₂ foams in filling mode. These tests are conducted according tothe operating protocol described above with containers which may berectangular dishes or tubes and according to the formulations detailedabove. Contamination is performed on two of the vertical walls of thedish (50 μl of solution containing 10⁸ spores/ml on each wall) or on thevertical wall of the tube.

For the tests in filling mode, six tests with a 5% NaOCl foam, one testwith a 7.5% NaOCl foam and five tests with a 5% H₂O₂ foam wereconducted. The results of these tests are shown in FIG. 6. The varioustypes of foam tests are suitable for decontaminating enclosed spaces infilling mode.

III.6. Evaluation of Decontamination Efficacy of Foams According toMoisture Percentage.

Tests are conducted in order to determine the biocidal efficacy of NaOCland H₂O₂ foams at different moisture percentages. These tests areconducted according to the biological operating protocol and accordingto the formulations detailed above.

The moisture percentage of the foam is modified following changes infoam generator settings. The generator is thus configured a first timeto obtain foams with 2.5% moisture and a second time to obtain 3%moisture. A test was conducted with a NaOCl foam at 3.5% moisture andanother at 4%. The same applied for an H₂O₂ for which a test wasconducted at 2.7% and another at 2.8% moisture.

The results of these tests are shown in FIG. 7. The NaOCl foam iseffective from 3.5% moisture (expansion 28.5) and the H₂O₂ from 2.7%moisture (expansion 37).

III.7. Evaluation of Decontamination Efficacy of Foams after Ageing ofSolutions.

Tests are conducted in order to determine the biocidal efficacy of NaOCland H₂O₂ foams after several weeks of storage. These tests are conductedaccording to the biological operating protocol and according to theformulations detailed above.

Tests are performed on the day of preparation of the solutions (t=0), 1week after (t=1 wk), 2 weeks after (t=2 wk) and 5 weeks after thepreparation thereof (t=5 wk). The initial liquid solutions from whichthe foams are produced are stored in a cold store at 4′C for the ageingtime.

A test is conducted with a 5% NaOCl foam and a 5% H₂O₂ foam at eachageing time. The results of these tests are shown in FIG. 8. The foamsretain Bt spore decontamination potential even after 5 weeks of storageof the initial foaming solution.

III.8. Evaluation of Foamability of Foaming Solutions and Stability OverTime of Corresponding Foams.

Foaming experiments are conducted in order to determine the foamabilityof the NaOCl and H₂O₂ after several weeks of storage. These experimentsare conducted with a commercial apparatus called Foamscan from Teclis.It is used to measure, in a 150 ml column and with an initial solutionvolume of 20 ml, not only the foaming rate for a given air flow rate(determined at 100 ml) but also the stability of the foam by stoppingair injection.

Therefore, a measurement is made, as a function of time, of thereduction in the quantity of liquid in the column until air injection isstopped (approximately 60 seconds, see FIGS. 9A and 9B). Then, from thetime the gas is stopped, the quantity of liquid in the column increasesmore or less quickly, indicating the drainage of the foam and thereofthe stability thereof.

In the presence of a viscosifying agent such as xanthan, a delay in theonset of drainage may be observed which is indicated by the existence ofa plateau before the increase in the level of liquid in the column. Theduration of this plateau indicates the stability of the foam. The ageingresults obtained at t=0, t=1 wk and t=5 wk, are illustrated in FIG. 9.

As such, for the 5% sodium hypochlorite solution and a quantity ofxanthan of 1.5 g/l (FIG. 9A), all the curves show an identical and totaltransfer (first part of the curve) of liquid into the foam. The decreaseis linear indicating that all of the air injected is captured to formthe foam. After switching off the air, the fresh foam (t=0 wk) exhibitsa plateau of approximately 180 s, then drainage starts slowly: after 10min, only 25% of the liquid has drained. After 1 week of storage, whilethe foamability is identical, the stability, on the other hand, islower: the drainage delay plateau observed is merely 40 s and thedrainage is more rapid (75% of liquid drains in 10 min). Thedecontamination efficacy tests demonstrated that the biocidal solutionremains foaming and that the corresponding NaOCl foam remains activeafter 5 weeks of storage.

For the 5% hydrogen peroxide solution and a quantity of xanthan of 1.5g/l (FIG. 9B), all the curves show an identical and total transfer(first part of the curve) of liquid into the foam. The decrease islinear indicating that all of the air injected is captured to form thefoam. After switching off the air, all of the foams exhibit a drainagedelay greater than 10 min. The H₂O₂ foams are more stable than the NaOClfoams.

III.9. Evaluation of the Adhesion of Foams on a Vertical Wall Accordingto Different Xanthan Concentrations.

These tests are intended to determine the adhesion of foam deposits on avertical wall by measuring the slippage of the foam over time. Foamdeposits of 3 different sizes were carried out with different solutionsaccording to the present invention and with different concentrations ofxanthan which is the viscosifying agent of the formulation. For thesetests, four xanthan concentrations are tested: 1.5 g/l, 2 g/l, 2.5 g/land 3 g/l.

These tests are conducted with, as a substrate, a wipe-off markerwhiteboard. This is a non-porous and very smooth material which makes itpossible to conduct these tests under the most difficult conditions. Theposition of the deposit at t=0 is recorded and, after various times haveelapsed, the slippage distance of the foam is measured.

The NaOCl and H₂O₂ foams adhere to the surface of a wipe-off markerwhiteboard. The slippage of the foam is slowed down considerably (meanslippage of 3 cm in 30 min) when the xanthan concentration is increasedto 3 g/l (FIG. 10).

III.10. Evaluation of Evaporation of Different Foams.

Tests are conducted in order to determine the evaporation rate of alayer of foam and the influence of the disinfecting agents thereon.These tests are conducted using a controlled-temperature and hygrometryclimatic chamber. It consists of evaporating horizontally approximately24 cm³ (4 cm×4 cm×1.5 cm) of foam in a stainless steel boat whilemeasuring the loss of mass over time, using a precision balance. Theclimatic chamber is set to a temperature of 22′C and a relative humidityof 40%.

The foam is generated by a static generator with beads and deposited inthe stainless steel boat. The latter is then placed in the balancesituated in the climatic chamber. The balance is entirely enclosed. Itindicates the mass of the foam contained in the boat, the boat havingbeen previously calibrated. A software program is used to record, every10 min, the mass measured by the balance in real time. A second softwareprogram is used to take photos inside the balance.

The foams generated for these tests are 5% NaOCl, 5% H₂O₂ and neutralfoams with 1.5 g/l or 3 g/l of xanthan. The duration of the tests isovernight or over a weekend.

The results of these tests are shown in FIG. 11 with the tests for theneutral foams, NaOCl foams and H₂O₂ foams in FIGS. 11A, 11B and 11C,respectively. The evaporation rate is constant for at least 300 min thenstarts to decrease for a low foam mass. It is also observed that, withNaOCl foams (FIG. 11B), after evaporation, a residue of sodium chlorideand sodium carbonate crystals remains, the mass whereof is low butmeasurable. By calculating the slope equation over the first 300 minutes(linear regression), it is observed that the directional coefficients ofthe slopes of all of the evaporation tests are relatively similar (mean−0.0019+/−0.0003), either with or without disinfectant and at bothxanthan concentrations. A test with a layer of water was conducted andthe evaporation displays the same kinetics. Therefore, the initialevaporation does not appear to be influenced by the foam formulation andcorresponds to the water evaporation. For 1 g of foam spread over 4 cmby 4 cm and over a thickness of 1.5 cm, evaporation is performed onaverage in 9 hours.

These tests were supplemented by depositing a layer of 5% NaOCl foamdeposited with a spatula on a plastic vertical surface contaminated withBt spore spots. This experiment was conducted under a ventilated hood inwhich the air flow accelerates the evaporation rate.

The decontamination efficacy measurements on Bt spores, according to thebiological operating protocol above, exhibit excellent efficacy (greaterthan 10⁶ inactivated spores).

As such, in 14 hours, the foam layer had entirely disappeared and thefoam liquid evaporated. After evaporation, a thin, transparent film ofglucopon and xanthan is observed, for each foam. Furthermore, for theNaOCl foam, small sodium chloride and sodium carbonate crystalsresulting from the evaporation reaction are also observed.

III.11. Evaluation of Retrieval of Foam by Suction.

Foam retrieval tests by suction were conducted with a liquid suctionmachine.

For this purpose, a 1 to 3 cm thick layer of a foam according to theinvention was applied by floating onto a vertical wall or a 301container was filled with a foam according to the invention. In bothapplications modes i.e. floating or filling, the foam is suitable forsuction.

REFERENCES

-   [1] EFT Holdings Inc. “MATERIAL SAFETY DATA SHEET NAME OF FINISHED    SOLUTION: EasyDECON® DF200-531X” Alabama 2008.    http://www.easydecon.com/easydecon/EasyDECON%20DF200%20MSDS.pdf-   [2] Patent application U.S. Pat. No. 7,276,468 on behalf of Sandia    Corporation, granted on 2 Oct. 2007.-   [3] EFT Holdings Inc. “Performance Data” Alabama 2011.    http://www.easydecon.com/easydecon/FactSheete248.html-   [4] Allen Vanguard—CASCAD™ Decontamination Foam, 2009.    http://reports.hms-online.org/ViewProduct.aspx?CategoryId=175&ProductId=721-   [5] “Biological Agent Decontamination Technology Testing” U.S. EPA.    Biological Agent Decontamination Technology Testing. U.S.    Environmental Protection Agency, Washington, D.C., EPA/600/R-10/087,    2010.-   [6] International application WO 2004/008463 on behalf of CEA and    COGEMA, published on 22 Jan. 2004.-   [7] “A quantitative kinetic theory of emulsion type, I. Physical    chemistry of the emulsifying agent” Gas/Liquid and Liquid/Liquid    Interface. Proceedings of the International Congress of Surface    Activity (1957): 426-438.-   [8] Regulation (EU) No. 528/2012 of 22 May 2012 concerning the    provision on the market and use of biocidal products.-   [9] International application WO 02/043847 on behalf of CEA,    published on 6 Jun. 2002.

1: A foam of a dispersion of gas bubbles in a foaming solution,consisting of, per litre of the solution: from 0.05% to 1.5% by weightof at least one foaming organic surfactant, from 0.05% to 0.8% by weightof at least one organic gelling or viscosifying agent, from 1% to 14% byvolume of at least one disinfecting agent, and water, wherein the foamhas an expansion between 20 and
 50. 2: The foam according to claim 1,wherein the at least one foaming organic surfactant is selected from thegroup consisting of a non-ionic foaming surfactant, an anionic foamingsurfactant, and a cationic foaming surfactant. 3: The foam according toclaim 1, wherein the at least one organic gelling or viscosifying agentis selected from the group consisting of a water-soluble polymer, ahydrocolloid, a heteropolysaccharide, a cellulose derivative, and apolysaccharide. 4: The foam according to claim 1, wherein the at leastone disinfecting agent is selected from the group consisting of achlorinated product, an aldehyde, and an oxidant. 5: The foam accordingto claim 1, wherein from 0.1 to 1.1% by weight of the at least onefoaming organic surfactant, from 0.15% to 0.3% by weight of the at leastone organic gelling or viscosifying agent, and either from 2% to 7.5% byvolume or from 5% to 14% by volume of the at least one disinfectingagent or of a mixture of disinfecting agents are present in the foamingsolution. 6: The foam according to claim 1, wherein from 0.1 to 1.1% byweight of an alkylpolyglucoside, from 0.15% to 0.3% by weight of xanthangum, and either from 2% to 7.5% by volume or from 5% to 14% by volume ofsodium hypochlorite or hydrogen peroxide are present in the foamingsolution. 7: A method for treating a surface contaminated with at leastone biological agent, the method comprising: contacting said surfacewith the foam according to claim
 1. 8: The method according to claim 7,wherein said surface is made of metal, metal alloy, steel, tinplate,silicon, glass containing silicates, silica glass, ceramic, brick,porcelain, cement, concrete, asphalt, stone, granite, wood, clay,plastic or a combination thereof. 9: The method according to claim 7,wherein said biological agent is at least one species or bio-toxicelement selected from the group consisting of a pathogenic spore,Gram−bacteria, Gram+bacteria, a toxin, and a virus. 10: The methodaccording to claim 7, wherein the contacting is performed by: applying,on said surface, said foam by spraying or by floating or filling astructure containing said surface with said foam. 11: The methodaccording to claim 10, further comprising: after said contacting, dryingsprayed or floated foam by evaporation, or draining foam used in fillingmode. 12: The method according to claim 7, further comprising: aftersaid contacting, either retrieving the foam by suction before completedrying or retrieving dry residue of the foam by suction or by wiping.